1. Field of the Invention
The present invention relates to an actuator used for a safety apparatus for an automobile, for example, relates to an actuator used for an operation of lifting a hood panel or the like in receiving a walker as a protection object.
2. Description of the Related Art
In a background art, there is an actuator of a safety apparatus for an automobile mounted to a vehicle of moving up a rear end side of a hood panel to be able to receive a walker by a hood panel per se by utilizing absorption of an energy in plastically deforming the hood panel (refer to, for example, Patent References 1, 2).
The actuators for moving up the hood panel are constituted as a piston cylinder type constituting a drive source by a gas generated in operating a gas generator to be able to be operated swiftly and constituted such that the gas constituting a working fluid generated by operating the gas generator is filled at inside of a cylinder and a piston rod contained at inside of the cylinder is moved up to move up the hood panel connected to an upper end side of the piston rod. Further, the piston rod is constituted by a structure of integrating a piston and a support rod capable of supporting the hood panel by being extended from the piston. Further, the actuator constituted as the piston cylinder type includes a lock mechanism of restricting a downward movement of the moved-up piston rod relative to the cylinder so as not to move down the hood panel after moving up the hood panel by filling the gas from the gas generator at inside of the cylinder.
Further, as the gas generator, a micro gas generator igniting a powder or a gas generating agent by inputting an operating signal, and according to the gas generator, a combustion gas of the powder or a gas generated by a chemical reaction (oxidation reaction· oxidation combustion reaction) of the gas generator is utilized as a gas of moving the piston rod.
Patent Reference 1: JP-A-2004-322735
Patent Reference 2: JP-A-2004-330913
However, according to the actuator of the background art, as a structure of a lock mechanism, there is constituted a structure in which an inner peripheral face side of the cylinder is arranged with a C ring elastically deformed in a diameter contracting direction, an outer peripheral face side of the piston rod is made to be slidable relative to the inner peripheral face substantially over an entire length of the cylinder, and a fitting groove for fitting the C ring is arranged at a position of the outer peripheral face of the piston rod intended to be locked.
Therefore, for example, when a kinetic energy of a walker is configured to be able to be absorbed by using a plastic deformation of not only a receiving member of the hood panel or the like for receiving the protection object of a walker or the like but bending of the rod per se or the like by changing an outer diameter dimension of the rod to adjust a rigidity of the rod moving forward, according to the actuator of the background art, there is constituted the structure of sliding the outer peripheral face substantially over the entire length of the rod to the inner peripheral face of the cylinder, and therefore, the change is not limited only to the rod but also an inner diameter of the cylinder needs to change, which cannot be dealt with easily.